Because it works. Leafy and stem vegetables wilt as they lose water, and keeping the humidity up around them slows that down. Misting is a genuine preservation measure for lettuce, greens, broccoli and asparagus, not just theater.
What to check
It also makes everything look fresher than it is, which is the part worth knowing. Water beads on a leaf read as "just picked" to a shopper, and they say nothing at all about when it was cut.
Avoidusing wetness as a freshness cue. On asparagus, judge the cut end. On broccoli, judge the stalk end and the bead tightness. On lettuce, judge the core color. Those survive the sprayers.
Some things do not want it at all. Mushrooms, tomatoes, potatoes, onions and most fruit are kept out of the mist because water on them shortens their life rather than extending it.
Noteit is worth shaking a misted bunch off before you bag it, since water you carry home is water sitting on the leaves in your fridge, which is where slime starts.
Common mistakeassuming the misted display is the fresh one. It is the humid one. The store is protecting the product, which is a good sign about the store, but it is not information about that particular bunch.
Written by the team behind RIPE, a free app that reads a photo of the whole produce pile and rings the ripest ones. Every cue above is one you can check with your own hands, and it all works with no app at all.